Extech Instruments LT45 User manual

Brand: Extech Instruments

Model: LT45

Category: Measuring, testing & control

Type: User manual

Extech Instruments LT45 is a LED Light Meter designed to measure the intensity of illumination of white, red, yellow, green, and blue LED light and visible light. It can also calculate luminous intensity (CD) using a distance-to-the-light value programmed by the user. The LT45 features overload indication, battery status icon, data hold, maximum/average/minimum (MAX/MIN) tracking, push-button Zero calibration adjustment, auto power off (with disable function), and auto ranging features.

User Manual

LED Light Meter

Model LT45

Additional User Manual Translations available at www.extech.com

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Introduction

Congratulations on your purchase of the Extech LT45 LED Light Meter that measures light from LED

lamps in addition to fluorescent, metal halide, high-pressure sodium and incandescent sources. The

LT45 is capable of measuring the illumination of white, red, yellow, green, and blue LEDs up to

400,000 Lux (40,000 Fc).

The LT45 can also calculate luminous intensity (CD) using a distance-to-the-light value programmed

by the user in meters or feet units.

The LT45 can store up to 99 readings for later recall and includes Overload indication, Battery status

icon, Data hold, Maximum/Average/Minimum (MAX/MIN) tracking, push-button Zero calibration

adjustment, Auto Power off (with disable function), and auto ranging features.

This instrument is shipped fully tested and calibrated and, with proper use, will provide years of

reliable service. Please visit our website (www.extech.com) to check for the latest version of this

User Guide, Product Updates, and Customer Support.

Features

 Overload Indication: LCD screen will show “OL” at the upper left-hand corner

 Battery strength status indication

 Display Update Rate: 2.5 times per second

 Spectral response near CIE luminous spectral efficiency ratings

 Cosine Angle corrected

 Conforms to JIS C 1609:1993 and CNS 5119 general class A Specifications

 Measures the intensity of illumination of white, red, yellow, green, and blue LED light and

visible light in Lux or foot-candles

 Calculates Luminous Intensity (CD)

 Data hold freezes displayed reading

 Maximum/Average/Minimum Memory Hold

 Zero adjustment

 Auto power off with disable function

 Automatic range adjust optimizes accuracy and resolution

 Manually store/recall up to 99 readings

 Complete with light sensor, protective sensor cover, and coiled cable expandable to 59”

(1.5m), 9V battery, and hard shell case

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Safety

 Do not operate the meter in environments where the following are present: explosive gases

(or materials), combustible gases (or materials), steam, or dust.

 Please replace the battery immediately when the battery symbol appears on the LCD.

 Do not touch the meter’s circuit board for any reason as static electricity or contamination

could damage the sensitive components.

 For Indoor use only. This instrument was designed for pollution degree 2.

Meter Description

1. Display (LCD)

2. Lux/Fc/CD unit select button

3. MEM/READ button (for 99 reading memory)

4. Up arrow button and MAX/MIN/AVG button

5. Power and Auto Power OFF control button

6. Zero Calibration button

7. Data Hold and Light source select button

8. Down arrow button

9. Coiled sensor connection cable

10. Photo detector

Note: The battery and tripod mount are located

on the back of the meter

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Operation

Power ON-OFF

Momentarily press the Power button to power the meter. To power the meter OFF,

momentarily press the Power button again.

Taking Measurements

1. Switch the meter ON

2. Remove the sensor’s protective cover to expose the light sensor dome. The display should

switch ON, if not check that fresh batteries are installed.

3. The meter measures the intensity of the light (illuminance) that strikes the sensor dome in

foot candles and lux units (1 fc = 10.76 lux) displaying the measured value on the LCD.

4. Use the LUX/FC/CD button to select Lux or Foot candle units (CD, luminous intensity, is

explained in the dedicated section ‘Luminous Intensity’). When ‘OL’ is displayed, the

measurement exceeds the meter’s range capability.

5. Position the meter and light source so that the light strikes the sensor dome perpendicularly.

Although the meter compensates for an incidence angle, optimum performance is achieved

with a smaller incidence angle.

6. The meter’s LCD can show a value up to 3999 on the large digits and when more digits are

needed to represent the reading two additional (smaller) digits appear to the right of the

larger digits, e.g. 3999

LUX/FC/CD Units

Momentary presses of the LUX/FC/CD button toggles Lux and FC (foot-candles) units. Press and

hold the button to enter the CD (luminous intensity) mode. Refer to ‘Luminous Intensity’ section

for further information.

Auto Power OFF

To save battery life the meter powers down automatically after approximately 5 minutes of

inactivity (no button presses).

Enable/Disable Auto Power Off

With the meter ON, press and hold the Power button until the APO clock symbol switches

OFF (the Auto Power OFF utility is now disabled and the user must manually switch the meter

off). To re-enable the Auto Power OFF utility, repeat this process. The Clock symbol will switch

ON when the Auto Power OFF utility is re-enabled.

Zero Calibration

1. Ensure that the protective cover is attached to the light sensor.

2. Power the meter and the LCD should display ‘0’.

3. Momenarily press the “ZERO” button and the ADJ (adjusting) icon will switch ON indicating

that the zero adjustment (calibration) is working. When the calibration is finished, the ADJ

icon will switch OFF and the meter will return to the normal operating mode.

4. If the protective cap is not covering the sensor when the ZERO calibration is started the LCD

display will read “CAP”. In this case, please cover the sensor with the cap and restart this

procedure.

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MAX/AVG/MIN Memory Mode

The meter can record the maximum, minimum, and average readings as described below:

1. Momentarily press the MAX/AVG/MIN button and the meter will begin to track the

maximum/average/minimum measurements; the “MIN” icon will display on the LCD

indicating that the meter is now displaying the minimum reading. The reading will not

change until a lower reading is registered.

2. Press the button again to switch from “MIN” to “MAX” where the meter will show the

maximum measurement value. The “MAX” icon will be displayed on the LCD.

3. Press the button again to change the mode from “MAX” to “AVG”, where the meter will

show the average of the readings taken since the button was first pressed. The “AVG”

icon will be displayed.

4. Press the button again to switch from “AVG” back to “MIN”.

To exit this mode, press and hold the button for at least 2 seconds. The MAX/AVG/MIN icons

should all be switched OFF when the unit returns to the normal operating mode.

Memory Record/Read Mode

1. Momentarily press the Mem/Read button to store a reading. The LCD will display a small ‘M’

icon on the lower left-hand area of the LCD along with the memory location number (1 to

99) representing the storage location for the recorded reading. Up to 99 readings can be

stored.

2. To review (read) the stored readings, press and hold the Mem/Read button until the ‘MEM’

icon appears at the top of the LCD. Now use the arrow buttons to scroll through the stored

readings. The small ‘M’ icon and the memory location counter (1 to 99) will be shown on the

lower left-hand corner of the LCD while the main display digits show the stored reading for

the selected memory location.

3. To store an average (AVG) reading, first access the AVG mode (See MIN/MAX/AVG section of

this guide) and while an average reading is displaying (AVG icon switched ON), momentarily

press the Mem/Read button for one second. The LCD will display ‘AVG M’ and the memory

location number (1 to 99) indicating that an average reading has been stored in the

numbered memory location.

4. When a stored reading is an AVG value, the screen will display ‘AVG’ on the lower left-hand

corner.

5. Momentarily press the Mem/Read button to exit the Memory mode and return to the

normal operating mode.

6. To clear all 99 memory locations: With the meter switched OFF, press and hold the

Mem/Read

and On/Off buttons simultaneously for two seconds. The meter will switch ON

and the screen will display “CLr” indicating that all of the 99 memory locations have been

erased.

Data Hold

Press the Hold button to freeze the displayed reading (the ‘HOLD’ icon will switch ON). Press the

button again to release the held reading (the ‘HOLD’ icon will switch OFF).

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Luminous Intensity (CD) Measurements

1. Press the On/Off button to turn power ON.

2. Press and hold the LX/FC/CD button until the meter’s unit designator switches to CD.

3. Use the arrow buttons to select ft (feet) or m (meter) units to represent the distance the

sensor will be from the light source.

4. Momentarily press the LX/FC/CD button; the smaller digits (lower-right hand corner of LCD)

will switch ON, these digits represent the distance to the light source.

5. Use the arrow buttons to set the distance from the center of the lamp to the measurement

base level. Press and hold an arrow button to scroll quickly.

6. Momentarily press the LX/FC/CD button.

7. Remove the protective sensor cap and place the sensor perpendicular to the light at the

programmed distance.

8. Read the Luminous Intensity calculation on the meter’s LCD display.

9. Press and hold the LX/FC/CD button to exit this mode.

 Luminous Intensity = illumination (Lx) x distance (ft

or m

)

 The programmable distance range is 0.01 ~ 30.47 m (0.01 ~ 99.99 ft.)

Light Source (L.S.) Selection

There are 10 light source selections (L0 – L9) each having a unique calibration correction factor

(multiplier). See the Light Source list below. The multipliers for locations L0 through L6 are fixed

for the lighting types listed. Locations L7 through L9 are extra locations that the user can

customize (with a multiplier from 0.001 to 1.999). To change the light source (L.S.) selection:

1. Press and hold the Hold/LS button for 2 seconds. The light source code, at the bottom center

of the LCD, will flash. Use the arrow buttons to select L0 through L9. The location’s multiplier

(correction factor) will be shown to the right of the Lx value (L8…1000, for example).

2. To customize a location, select L7, L8 or L9 and, once selected, momentarily press the

Hold/LS button to enter the multiplier programming mode. Now use the arrow keys to

change the multiplier. Press and hold an arrow button to scroll faster.

3. When finished, press and hold the Hold/LS button for at least 1 second to confirm the edit

and exit this mode.

Light Source

L0: Standard incandescent light source

L1: LED white daylight

L2: LED AMBER (YELLOW) light

L3: LED GREEN light

L4: LED RED light

L5: LED BLUE light

L6: Not used

L7~L9: Programmable User Custom Locations (preset to 1.00)

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Measurement Considerations and User Tips

 For maximum accuracy allow the light being measured to fall directly on the sensor as

perpendicular as possible with a minimal angle of incidence.

 When the meter is not in use, please keep the protective cap in place, covering the light sensor.

This will prolong the life of the sensor.

 When the meter is to be stored for long periods, please remove the battery and store it

separately. Batteries can leak and cause damage to the meter’s components.

 Avoid areas of high temperature and humidity when using this instrument.

 See Specifications for accuracy with angular deviation.

Battery Replacement and Maintenance

Cleaning and storage

1. The white plastic sensor dome should be cleaned with a damp cloth when necessary. Use

only a mild soap if needed. Do not use solvents, abrasives, or harsh detergents to clean the

dome.

2. Store the meter in an area with moderate temperature and relative humidity.

Battery Replacement

When the battery power decreases to a critical level, the battery symbol will appear as empty on

the LCD. Replace the 9V battery located in the rear battery compartment. The battery

compartment slides easily downward for removal (in the direction of the printed arrow on the

rear of the meter). Ensure that the compartment cover is securely fastened before using the

meter.

Never dispose of used batteries or rechargeable batteries in household waste.

As consumers, users are legally required to take used batteries to appropriate collection sites,

the retail store where the batteries were purchased, or wherever batteries are sold.

Disposal: Do not dispose of this instrument in household waste. The user is obligated to take

end-of-life devices to a designated collection point for the disposal of electrical and electronic

equipment,

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Specifications

Sampling rate

2.5 times per second (digital display)

Display

6-digit LCD with battery icon, measurement overload, and

other function indicators

Sensor (detector)

Silicon photodiode with spectral response filter and cosine

correction

Ranges and Resolution

*Above 3999, the LCD uses

smaller digits on the right

side

Lux

Foot-candles

399.9

0.1

39.99

0.01

3999

399.9

0.1

*39999

3999

*399999

100

*39999

Auto-range

The meter automatically ranges the display

Accuracy

(1 Fc = 10.76 Lux)

LED light:

± (3% of reading + 3 digits) up to 500 Lux (46Fc)

± (3% of reading) above 500 Lux (46Fc)

Visible Light:

Calibrated to standard incandescent lamp 2856

K at an

ambient temperature of 23

± (6% of Reading + 3 digits)

Angle deviation from cosine

characteristics

(Cosine Angular corrected

per JIS C 1609:1993 and CNS

5119 general A class)

○

±2%

○

±6%

○

±25%

LED Types Meter measures white, red, yellow, green, and blue LED light

Operating conditions Temperature: 5 to 40

C (41 to 104

F); Humidity: < 80% RH

Operation Altitude Up to 2000m (7000’)

Storage Temperature/RH -10 to 60

C (14 to 140

F); Humidity: < 70% RH

Battery status indication Battery symbol appears empty when battery voltage reaches critical level

Power supply 9V battery

Auto Power OFF Meter powers down after 5 minutes of inactivity (can be defeated)

Dimensions Meter: 38 x 55 x 130mm (1.5 x 2.2 x 5.1”)

Sensor: 25 x 44 x 80mm (9.8 x 2.2 x 3.1”)

Cable length: 1.5m (4.9 ft.)

Weight Approx. 250g (8.8 oz.) with battery installed

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Appendix

Spectral Sensitivity

Peak sensitivity wavelength: 550nm

ISO-9001 Certified

www.extech.com

RELATIVE SENSITIVITY (%)

WAVELENGTH (nm)

LT45

Extech Instruments LT45 User manual

Brand: Extech Instruments

Model: LT45

Category: Measuring, testing & control

Type: User manual

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Extech Instruments LT45 User manual

Extech Instruments LT45 User manual

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